Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Position Independent Executable (PIE) support will allow to extended the KASLR randomization range below the -2G memory limit. Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx> --- arch/x86/entry/entry_64.S | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 49167258d587..15bd5530d2ae 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -194,12 +194,15 @@ entry_SYSCALL_64_fastpath: ja 1f /* return -ENOSYS (already in pt_regs->ax) */ movq %r10, %rcx + /* Ensures the call is position independent */ + leaq sys_call_table(%rip), %r11 + /* * This call instruction is handled specially in stub_ptregs_64. * It might end up jumping to the slow path. If it jumps, RAX * and all argument registers are clobbered. */ - call *sys_call_table(, %rax, 8) + call *(%r11, %rax, 8) .Lentry_SYSCALL_64_after_fastpath_call: movq %rax, RAX(%rsp) @@ -334,7 +337,8 @@ ENTRY(stub_ptregs_64) * RAX stores a pointer to the C function implementing the syscall. * IRQs are on. */ - cmpq $.Lentry_SYSCALL_64_after_fastpath_call, (%rsp) + leaq .Lentry_SYSCALL_64_after_fastpath_call(%rip), %r11 + cmpq %r11, (%rsp) jne 1f /* @@ -1172,7 +1176,8 @@ ENTRY(error_entry) movl %ecx, %eax /* zero extend */ cmpq %rax, RIP+8(%rsp) je .Lbstep_iret - cmpq $.Lgs_change, RIP+8(%rsp) + leaq .Lgs_change(%rip), %rcx + cmpq %rcx, RIP+8(%rsp) jne .Lerror_entry_done /* @@ -1383,10 +1388,10 @@ ENTRY(nmi) * resume the outer NMI. */ - movq $repeat_nmi, %rdx + leaq repeat_nmi(%rip), %rdx cmpq 8(%rsp), %rdx ja 1f - movq $end_repeat_nmi, %rdx + leaq end_repeat_nmi(%rip), %rdx cmpq 8(%rsp), %rdx ja nested_nmi_out 1: @@ -1440,7 +1445,8 @@ nested_nmi: pushq %rdx pushfq pushq $__KERNEL_CS - pushq $repeat_nmi + leaq repeat_nmi(%rip), %rdx + pushq %rdx /* Put stack back */ addq $(6*8), %rsp @@ -1479,7 +1485,9 @@ first_nmi: addq $8, (%rsp) /* Fix up RSP */ pushfq /* RFLAGS */ pushq $__KERNEL_CS /* CS */ - pushq $1f /* RIP */ + pushq %rax /* Support Position Independent Code */ + leaq 1f(%rip), %rax /* RIP */ + xchgq %rax, (%rsp) /* Restore RAX, put 1f */ INTERRUPT_RETURN /* continues at repeat_nmi below */ UNWIND_HINT_IRET_REGS 1: -- 2.14.2.920.gcf0c67979c-goog _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
